Full Idea
If someone passes a law and it does not turn out to be in accord with what is useful in mutual associations, this no longer possesses the nature of justice.
Gist of Idea
A law is not just if it is not useful in mutual associations
Source
Epicurus (Principle Doctrines ('Kuriai Doxai') (frags) [c.290 BCE], 37)
Book Reference
Epicurus: 'The Epicurus Reader', ed/tr. Inwood,B. /Gerson,L. [Hackett 1994], p.35